One or more aspects relate, in general, to processing within a computing environment, and in particular, to processing associated with address translation data structures of a virtual environment.
In computing environments that support virtualization technology, an operating system may be running on a virtual machine on a processor that supports multiple levels of address translation tables. In such an environment, the operating system is a guest of a hypervisor also executing in the computing environment.
Further, in such environments, dynamic address translation (DAT) may be performed during a memory reference to translate a virtual address into a corresponding real or absolute address. This translation typically includes a walk, referred to as a page or DAT walk, of multiple levels of address translation tables in order to determine the real address. This is time consuming, and thus, to improve performance for future translation requests, the virtual address to real or absolute address mapping is stored in an entry of a structure associated with address translation, such as a translation look-aside buffer (TLB) or other such structure.
The translation look-aside buffer is a cache used by the memory management hardware to improve virtual address translation speed. The next time translation for a virtual address is requested, the TLB is checked. If the translation is in the TLB, the real or absolute address is retrieved from the TLB. Otherwise, the DAT walk is performed once again.
At times, it is necessary to purge some or all of the TLB entries used by a particular processor. When this occurs, there is often a performance loss due to having to walk the DAT tables again to recreate the entries.